Method for sterilizing water treatment apparatus having plurality of tanks

ABSTRACT

Provided is a method for sterilizing a water treatment apparatus having a plurality of tanks. The method includes, performing a sterilization preparation process to drain purified water from the first tank until a first amount of purified water is left, performing a sterilizing process to sterilize the first tank by supplying the sterilized water supplied from the sterilizing module, to drain water from the first tank through a first water outlet pipe until a second amount of water is left in the first tank, and to drain the second amount of water remaining in the first tank into the second tank through a second water outlet pipe.

PRIORITY

This application is a National Phase Entry of PCT InternationalApplication No. PCT/KR2012/004115 filed May 24, 2012, and claimspriority to Korean Patent Application Nos. 10-2011-0052195,10-2011-0073507 and 10-2012-0051326 filed with the Korean IntellectualProperty Office on May 31, 2011, Jul. 25, 2011 and May 15, 2012,respectively, the content of each of which is incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a method for sterilizing a watertreatment apparatus having a plurality of tanks, and more particularly,to a method for sterilizing tanks and flow passages of a water treatmentapparatus having a plurality of tanks.

BACKGROUND ART

In general, water purifiers may be classified into ultra filtration (UF)membrane water purifiers and reverse osmosis (RO) membrane waterpurifiers, depending on a water purifying method carried out thereby.

Among them, the RO membrane water purifier has been known as beingsuperior to other water purifying schemes in terms of removingpollutants.

The RO membrane water purifier may include a filtering unit including asediment filter that receives raw water from a faucet and removes dustparticles, dregs, various suspended bodies, and the like therefrom,through 5-micron fine filters; a pre-carbon filter that removescarcinogens (e.g., trihalomethane (THM)), synthetic detergents, harmfulchemicals (e.g., insecticides), residual chlorine components, and thelike, by activated carbon adsorption; an RO membrane filter thatincludes a 0.0001-micron RO membrane, removes heavy metals (e.g., leadand arsenic), sodium, various germs, and the like, and dischargesconcentrated water through a drain pipe; and a post-carbon filter thatremoves unpleasant odors, tastes, and colors contained in water havingpassed through the RO membrane filter.

The UF membrane water purifier uses a UF membrane filter instead of anRO membrane filter. The UF membrane filter is a porous filter havingtens to hundreds of nanometer (nm) pores, which removes pollutants inwater through numerous fine pores that are distributed on a membranesurface.

As described above, the RO membrane water purifier or the UF membranewater purifier may use four filters. However, the RO membrane waterpurifier or the UF membrane water purifier may additionally use anantibacterial filter or a functional filter. Moreover, the RO membranewater purifier or the UF membrane water purifier may be used as acombinational filter having functions of a variety of filters. Forexample, a function of a sediment filter and a function of a pre-carbonfilter may be embodied in a single combinational filter.

However, in such a water purifier, a post-carbon filter or the like maybe easily polluted by bacteria, and bacteria may flow into a storagetank in water. Therefore, bacteria may proliferate in the storage tank.In addition, external bacteria or microorganisms may pass throughpurified water stored in the storage tank and proliferate therein, andwater scale may be formed on the inner wall of the storage tank.

In order to sterilize bacteria or microorganisms having proliferated ina storage tank, there is proposed a technology that sterilizes a storagetank and a purified water drainage passage by adding separatesterilizing chemicals thereto.

However, this method of supplying sterilizing chemicals may beburdensome and inefficient in terms of sterilization management becausea user or a water purifier manager needs to separately perform asterilizing chemical supply operation. That is, in the case of supplyingsterilizing chemicals, a user needs to periodically insert sterilizingchemicals when an automatic injection of sterilizing chemicals isimpossible. Also, even in the case that automatic injection ofsterilizing chemicals is possible, a user also needs to periodicallyinsert sterilizing chemicals. Therefore, this method is veryinconvenient to a user.

Furthermore, in the case of injecting sterilizing chemicals, aconcentration of the sterilizing chemicals may be unnecessarily high. Insome cases, a user or a manager may inject a large amount of sterilizingchemicals or a small amount of sterilizing chemicals. Therefore,sterilizing chemicals may remain in a water purifier after a cleaningprocess. Therefore, after the cleaning process, it is necessary toperform a rinsing process several times. If the rinsing process is notadequately performed, the remaining sterilizing chemicals may cause harmto a user' health, and a user may experience unpleasant odors from thesterilizing chemicals.

Moreover, since the water purifier manager needs to perform thesterilizing chemical supply operation, costs for sterilizing the waterpurifier may be incurred. Thus, the user may feel burdened by servicecharges.

In particular, the water purifier is not sterilized or cleaned byitself. In most cases, the water purifier is sterilized or cleaned by aservice agent. Therefore, it is very inconvenient to a user, and thereliability of the water purifier may be degraded over time.

Conditions in which sterilizing chemicals dissolve or flow out from atank may also be different depending on a water purifier operationcondition (for example, a raw water pressure, a flow rate, or the like).For example, when a flow rate is low, a sterilizing concentration may berelatively high. On the contrary, when a flow rate is high, asterilizing concentration may be low. Therefore, it is very difficult tocontrol the sterilization. When a concentration of sterilizing chemicalsis high, unpleasant odors may be generated.

Since the main sterilizing material used in sterilizing chemicals isOCl—, either having a low pH or a very high pH, a lot of odor may begenerated thereby. Also, sterilizing performance is merely 1/70 of thatof HOCl. Therefore, a large amount of OCl— sterilizing material ascompared to HOCl may be required for sterilizing a tank having the samecapacity. As will later be described, sterilizing performance may besignificantly degraded as compared to a case of using an electrolyzer toproduce a sterilizing material mainly made of HOCl, containing a mixedoxidant (MO).

In order to solve a problem of a water purifier which is sterilizedusing such sterilizing chemicals, there has been proposed a method ofautomatically sterilizing a storage tank using an electrolyzer. FIG. 1illustrates a water treatment apparatus disclosed in Korean PatentApplication Publication No. 2009-0128785.

As illustrated in FIG. 1, a conventional water treatment apparatus 10filters raw water, supplied from a raw water supply unit such as a watermain 15, through a water purifying filter 14, stores the filtered waterin a storage tank 13, and supplies the filtered water through adispenser 17 when a user requests the supply of water. In this case, ifpollution of purified water stored in the storage tank 13 is detected bya pollution level sensor 13 a provided in the storage tank 13, or apredetermined period of time has elapsed, hypochlorous acid may begenerated using a chloride supply device 11 and an electrolysis device12, and be supplied to the storage tank 13. A process of cleaning thestorage tank 13, which is disclosed in Korean Patent Application No.2009-0128785, will be described below in detail.

When it is necessary to clean the storage tank 13 through the pollutionlevel sensor 13 a, water stored in the storage tank 13 is completelydrained into sewage 16 using an extraction pipe G and the dispenser 17or through a drain pipe F. Alternatively, most water stored in thestorage tank 13 is drained into a low water level or a position near afloor. When the drainage of water stored in the storage tank 13 iscompleted, a valve Vg or Vf is shut off. In order to supply chlorides,such as NaCl or KCl, from the chloride supply device 11 to theelectrolysis device 12, and generate a chloride aqueous solution, rawwater (service water) may be supplied through a raw water supply pipe B,without passing through the water purifying filter 14, or purified waterfiltered by the water purifying filter 14 may be supplied through a rawwater supply pipe C disposed at a rear end of the water purifying filter14. In this case, when the chloride and raw water (service water) orpurified water is supplied to the electrolysis device 12 and asufficient period of time has elapsed to dissolve the chloride, anaqueous solution containing hypochlorous acid is generated through theelectrolysis (oxidation-reduction reaction) of the chloride aqueoussolution by applying a voltage to electrodes 12 a of the electrolysisdevice 12. The storage tank 13 is fully filled with the generatedhypochlorous acid aqueous solution and is maintained during apredetermined period time necessary to sterilize and clean the storagetank 13. After the predetermined period of time has elapsed, thehypochlorous acid aqueous solution is drained from the storage tank 13.In order to remove the hypochlorous acid aqueous solution, water havingpassed through the water purifying filter 14 is supplied to the storagetank 13 through the purified water supply pipe D up to a level of thestorage tank 13 equal to that when full, or service water which has notpassed through the water purifying filter 14 is supplied to the storagetank 13 through a rinse pipe H up to a full water level of the storagetank 13. After a predetermined period of time has elapsed, a rinseprocess of draining rinse water stored in the storage tank 13 isperformed several times. In this way, the process of cleaning thestorage tank 13 is completed. Then, raw water is filtered through thewater purifying filter 14, and purified water is supplied to the storagetank 13, so that a user can use the purified water.

Since the conventional water treatment apparatus is provided with asingle storage tank 13, it is easy to sterilize and clean the storagetank. However, since a water treatment apparatus having an ice maker anda plurality of tanks has recently been introduced, there is a need for asterilizing method that takes into consideration water flow among aplurality of tanks.

DISCLOSURE OF INVENTION Technical Problem

An aspect of the present invention provides a method for sterilizingtanks and flow passages of a water treatment apparatus having aplurality of tanks.

Solution to Problem

According to an aspect of the present invention, there is provided amethod for sterilizing a water treatment apparatus having a sterilizingmodule, which generates or receives sterilized water and supplies thesterilized water, a first tank, and a second tank, the method including:performing a sterilization preparation process to drain purified waterfrom the first tank until a first amount of purified water is left inthe first tank; performing a sterilizing process to sterilize the firsttank by supplying the sterilized water supplied from the sterilizingmodule to the first tank, to drain water from the first tank through afirst water outlet pipe until a second amount of water is left in thefirst tank, and to drain the second amount of water remaining in thefirst tank into the second tank through a second water outlet pipe; andperforming a cleaning process to clean the first tank by supplyingpurified water to the first tank, and to drain the purified water usedto clean the first tank into the second tank.

In the sterilizing process, water of the first tank may be drained intothe second tank through the second water outlet pipe until a secondamount of water is left in the first tank, and the second amount ofwater remaining in the first tank may be drained through the first wateroutlet pipe.

The first water outlet pipe may be configured to supply water to anintermediate device included in the water treatment apparatus, and theintermediate device may be connected to the second tank and configuredto bypass water supplied from the first water outlet pipe to the secondtank.

The intermediate device may be any one of a third tank, an ice maker, acarbonated water maker, and a syrup addition device.

The sterilization preparation process may include: supplying a presetvolume of purified water to the first tank; and draining the purifiedwater stored in the first tank during a first draining period, the firstdraining period being a period of time taken to drain an amount of watercorresponding to a difference between the preset volume and the firstamount of water.

The preset volume may be a maximum storage amount of the first tank.

The method may further include draining water stored in the second tankafter the sterilization preparation process.

The sterilizing process may include: sterilizing the first tank bysupplying a preset volume of the sterilized water supplied from thesterilizing module to the first tank; draining the sterilized waterstored in the first tank through the first water outlet pipe during asecond draining period; and draining the water remaining in the firsttank through the second water outlet pipe, the second draining periodbeing a period of time taken to drain an amount of water correspondingto a difference between the preset volume and the second amount ofwater.

The sterilizing process may include: sterilizing the first tank bysupply a preset volume of the sterilized water supplied from thesterilizing module to the first tank; draining the sterilized waterstored in the first tank through the second water outlet pipe during asecond draining period; and draining the water remaining in the firsttank through the first water outlet pipe, the second draining periodbeing a period of time taken to drain an amount of water correspondingto a difference between the preset volume and the second amount ofwater.

The method may further include draining sterilized water stored in thesecond tank after the sterilizing process.

The cleaning process may include: cleaning the first tank by supplying apreset volume of purified water to the first tank; draining the suppliedpurified water stored in the first tank into the second tank; anddraining the purified water drained into the second tank.

The purified water may be supplied to the first tank at the same time asthe draining of the purified water drained into the second tank, or thepurified water may be supplied to the first tank after the draining ofthe purified water drained into the second tank.

The first tank may include: a first water outlet pipe configured totransfer water stored in the first tank to an intermediate deviceincluded in the water treatment apparatus; a second water outlet pipeconfigured to transfer water stored in the first tank to the secondtank; and a water intake pipe configured to drain water stored in thefirst tank to the outside. The first water outlet pipe, the water intakepipe, and the second water outlet pipe may be installed on the side ofthe first tank in order from top to bottom.

The second tank may include: a drain line configured to drain waterstored in the second tank; a drain valve configured to open/close thedrain line; and a drain pump installed in the drain line.

The first amount of water may be determined, depending on a targetdilution level of the sterilized water.

When the second amount of water is stored in the first tank, a height ofa water surface may fall to within a range between a height of the waterintake pipe and a height of the first water outlet pipe.

The sterilizing module may generate the sterilized water by using one ofan electrolytic sterilizer employing electrolysis and a chemicalsterilizer employing sterilizing chemicals.

According to another aspect of the present invention, there is provideda method for sterilizing a water treatment apparatus having asterilizing module, which generates or receives sterilized water andsupplies the sterilized water, a first tank, a second tank, and anintermediate device, the method including: performing a sterilizationpreparation process to drain purified water from the first tank into thesecond tank until a first amount of purified water is left in the firsttank, and to drain purified water from the second tank until a secondamount of purified water is left in the second tank; performing a firststerilizing process to sterilize the first tank by supplying sterilizedwater supplied from the sterilizing module thereto, and to drain waterfrom the first tank into the second tank until a third amount of wateris left in the first tank; performing a second sterilizing process todrain sterilized water from the second tank into the intermediate deviceuntil a fourth amount of sterilized water is left in the second tank;performing a third sterilizing process to drain the second amount ofwater remaining in the first tank into the second tank; performing afourth sterilizing process to drain the sterilized water stored in thesecond tank; and performing a cleaning process to clean the first tankby supplying purified water to the first tank, and to drain the purifiedwater used to clean the first tank into the second tank.

In the sterilizing process, when water of the first tank is drained intothe second tank until the third amount of water is left in the firsttank during the first sterilizing process, the second amount of waterremaining in the first tank is drained into the intermediate deviceduring the third sterilizing process, and a fourth amount of thesterilized water stored in the second tank is drained into theintermediate device during the second sterilizing process.

In the sterilizing process, when water of the first tank is drained intothe second tank until the third amount of water is left in the firsttank during the first sterilizing process, the second amount of waterremaining in the first tank may be drained into the intermediate deviceduring the third sterilizing process, and a fourth amount of thesterilized water stored in the second tank may be drained into theintermediate device during the second sterilizing process.

When the first tank is sterilized by supplying the sterilized watersupplied from the sterilizing module thereto, water of the first tankmay be drained into the intermediate device until the third amount ofwater is left in the first tank, the second amount of water remaining inthe first tank may be drained into the second tank, and a fourth amountof the sterilized water stored in the second tank may be drained intothe intermediate device.

The method may further include a fourth sterilizing process to drain thesterilized water stored in the second tank after the third sterilizingprocess.

The intermediate device may be any one of a third tank, an ice maker, acarbonated water maker, and a syrup addition device.

The sterilization preparation process may include: draining water fromthe second tank; supplying a preset volume of purified water to thefirst tank; draining the purified water stored in the first tank intothe second tank during a first draining period; and draining thepurified water stored in the second tank during a second drainingperiod. The first draining period may be a period of time taken to drainan amount of water corresponding to a difference between the presetvolume and the first amount of water, and the second draining period maybe a period of time taken to drain an amount of water corresponding to aresult of a subtraction of the first amount of water and the secondamount of water from the preset volume.

The first sterilizing process may include: sterilizing the first tank bysupplying a preset volume of the sterilized water supplied from thesterilizing module to the first tank; and draining the sterilized waterstored in the first tank into the second tank during a third drainingperiod. The third draining period may be a period of time taken to drainan amount of water corresponding to a difference between the presetvolume and the third amount of water.

In the second sterilizing process, the sterilized water may be drainedfrom the second tank during a fourth draining period. The fourthdraining period may be a period of time taken to drain the fourth amountof water from the second tank.

The cleaning process may include: cleaning the first tank by supplying apreset volume of purified water to the first tank; draining the suppliedpurified water stored in the first tank into the second tank; drainingsome of the purified water from the second tank into the intermediatedevice; and draining the rest of the purified water from the secondtank.

The sterilizing module may generate the sterilized water by using one ofan electrolytic sterilizer employing electrolysis and a chemicalsterilizer employing sterilizing chemicals.

The preset volume may be a maximum storage amount of the first tank.

According to another aspect of the present invention, there is provideda method for sterilizing a water treatment apparatus having asterilizing module, which generates or receives sterilized water andsupplies the sterilized water, a first tank, a second tank, and anintermediate device, the method including: performing a sterilizationpreparation process to drain purified water from the first tank into thesecond tank until a first amount of purified water is left in the firsttank, and to drain purified water from the second tank until a secondamount of water is left in the second tank; performing a firststerilizing process to sterilize the first tank by supplying sterilizedwater supplied from the sterilizing module thereto, and to drain waterfrom the first tank into the second tank until a third amount of wateris left in the first tank; performing a second sterilizing process todrain sterilized water from the second tank into the intermediate deviceuntil a fourth amount of sterilized water is left in the second tank;performing a third sterilizing process to drain the second amount ofwater remaining in the first tank into the intermediate device;performing a first cleaning process to clean the first tank by supplyingpurified water to the first tank, to drain some of the purified waterused to clean the first tank into the intermediate device, and to drainthe rest of the purified water into the second tank; and performing asecond cleaning process to drain some of the purified water from thesecond tank, and to drain the rest of the purified water from the secondtank.

The intermediate device may be any one of a third tank, an ice maker, acarbonated water maker, and a syrup addition device.

The sterilization preparation process may include: draining water fromthe second tank; supplying a preset volume of purified water to thefirst tank; draining the purified water stored in the first tank intothe second tank during a first draining period; and draining thepurified water stored in the second tank during a second drainingperiod. The first draining period may be a period of time taken to drainan amount of water corresponding to a difference between the presetvolume and the first amount of water, and the second draining period maybe a period of time taken to drain an amount of water corresponding to aresult of a subtraction of the first amount of water and the secondamount of water from the preset volume.

The first sterilizing process may include: sterilizing the first tank bysupplying a preset volume of the sterilized water supplied from thesterilizing module to the first tank; and draining the sterilized waterstored in the first tank into the second tank during a third drainingperiod. The third draining period may be a period of time taken to drainan amount of water corresponding to a difference between the presetvolume and the third amount of water.

In the second sterilizing process, the sterilized water may be drainedfrom the second tank during a fourth draining period. The fourthdraining period may be a period of time taken to drain the fourth amountof water from the second tank.

The first cleaning process may include: cleaning the first tank bysupplying a preset volume of purified water to the first tank; drainingsome of the supplied purified water stored in the second tank into theintermediate device; and draining the rest of the purified water storedin the first tank into the second tank.

The second cleaning process may include: draining some of the purifiedwater stored in the second tank into the intermediate device; anddraining the rest of the purified water stored in the second tank.

The sterilizing module may generate the sterilized water by using one ofan electrolytic sterilizer employing electrolysis and a chemicalsterilizer employing sterilizing chemicals.

According to another aspect of the present invention, there is provideda method for sterilizing a water treatment apparatus having asterilizing module, which generates or receives sterilized water and thesterilized water, a first tank, a second tank, and an intermediatedevice, the method including: performing a sterilization preparationprocess to drain purified water from the first tank until a first amountof purified water is left in the first tank; performing a sterilizingprocess to sterilize the first tank by supplying sterilized watersupplied from the sterilizing module thereto, to drain water from thefirst tank into the second tank until a second amount of water is leftin the first tank, and to drain the second amount of water remaining inthe first tank into the intermediate device; and performing a cleaningprocess to clean the first tank by supplying purified water to the firsttank, to drain some of the purified water used to clean the first tankinto the second tank, and to drain the rest of the purified water intothe intermediate device.

The intermediate device may be any one of a third tank, an ice maker, acarbonated water maker, and a syrup addition device.

The sterilization preparation process may include: supplying a presetvolume of purified water to the first tank; and draining the purifiedwater stored in the first tank into the second tank during a firstdraining period. The first draining period may be a period of time takento drain an amount of water corresponding to a difference between thepreset volume and the first amount of water.

The sterilizing process may include: sterilizing the first tank bysupplying a preset volume of the sterilized water supplied from thesterilizing module to the first tank; draining the sterilized waterstored in the first tank into the second tank during a second drainingperiod, the second draining period being a period of time taken to drainan amount of water corresponding to a difference between the presetvolume and the second amount of water; and draining water remaining inthe first tank into the intermediate device.

The cleaning process may include: cleaning the first tank by supplying apreset volume of purified water to the first tank; draining some of thesupplied purified water stored in the first tank into the second tank;draining the rest of the supplied purified water stored in the firsttank into the intermediate device; and draining the purified waterstored in the second tank.

The sterilizing module may generate the sterilized water by using one ofan electrolytic sterilizer employing electrolysis and a chemicalsterilizer employing sterilizing chemicals.

The preset volume may be a maximum storage amount of the first tank.

Advantageous Effects of Invention

According to exemplary embodiments of the present invention, a methodfor sterilizing a water treatment apparatus having a plurality of tanksmay sterilize and clean a first tank and a second tank while preventingsterilized water from diffusing into a water intake pipe.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a block diagram schematically illustrating a configuration ofa conventional water treatment apparatus;

FIG. 2 is a schematic diagram illustrating a configuration of a watertreatment apparatus having a plurality of tanks, to which a sterilizingmethod according to an exemplary embodiment of the present invention isapplied;

FIG. 3 is a flow diagram illustrating a method for sterilizing a watertreatment apparatus having a plurality of tanks, according to anexemplary embodiment of the present invention;

FIG. 4 is a flow diagram illustrating a detailed flow of a sterilizationpreparation process in the method for sterilizing the water treatmentapparatus, according to an exemplary embodiment of the presentinvention;

FIG. 5 is a flow diagram illustrating a detailed flow of a sterilizingprocedure in the method for sterilizing the water treatment apparatus,according to an exemplary embodiment of the present invention;

FIG. 6 is a flow diagram illustrating a detailed flow of a cleaningprocedure in the method for sterilizing the water treatment apparatus,according to an exemplary embodiment of the present invention;

FIG. 7 is a schematic diagram illustrating a configuration of a watertreatment apparatus having a plurality of tanks, to which a sterilizingmethod according to another exemplary embodiment of the presentinvention is applied;

FIG. 8 is a flow diagram illustrating a method for sterilizing a watertreatment apparatus having a plurality of tanks, according to anotherexemplary embodiment of the present invention;

FIG. 9 is a flow diagram illustrating a detailed flow of a sterilizationpreparation process in the method for sterilizing the water treatmentapparatus having a plurality of tanks, according to another exemplaryembodiment of the present invention;

FIG. 10 is a schematic diagram illustrating a configuration of a watertreatment apparatus having a plurality of tanks, to which a sterilizingmethod according to another exemplary embodiment of the presentinvention is applied;

FIG. 11 is a flow diagram illustrating a method for sterilizing a watertreatment apparatus having a plurality of tanks, according to anotherexemplary embodiment of the present invention; and

FIG. 12 is a schematic diagram illustrating a configuration of a watertreatment apparatus having a plurality of tanks, to which a sterilizingmethod according to another exemplary embodiment of the presentinvention is applied.

BEST MODE FOR CARRYING OUT THE INVENTION

Exemplary embodiments of the present invention will now be described indetail with reference to the accompanying drawings. However, in thedescription of the operational principles associated with theembodiments of the present invention, a detailed description of knownart inventions or constructions is omitted because it may obscure thespirit of the present invention unnecessarily

In order to clearly describe the exemplary embodiments of the presentinvention, parts unrelated to the present invention are omitted. Thesame or equivalent elements are referred to as the same referencenumerals throughout the specification.

Unless explicitly described to the contrary, the terms “include” and“have” will be understood to imply the inclusion of stated elements butnot the exclusion of any other elements.

Water treatment apparatuses may be used to treat water or wastewater andproduce ultra-pure water, and may be used for various purposes such asindustrial purposes and domestic purposes (including business purposes).However, the present invention particularly relates to water treatmentapparatuses that are used to produce drinking water. Since watertreatment apparatuses for producing drinking water receive raw water (orwater), filter the raw water, and generate purified water for drinking,they will be referred to as water purifiers in a narrow sense. Suchwater purifiers may be configured to receive raw water (or water),filter the raw water with a filtering unit, and supplynormal-temperature purified water to users, and may also be configuredto heat or cool the normal-temperature purified water and supply hotwater or cold water to users.

Among the water treatment apparatuses for producing drinking water,there are functional water generators that supply a variety of types offunctional water, such as ionized water, carbonated water, andoxygenated water, as well as purified water. In addition, there arewater heaters, water coolers, ice makers and the like thatheat/cool/freeze water received from a water supply unit such as a watertank. In this specification, the term “water treatment apparatus” isused as a general term for a water purifier, a functional watergenerator, a water heater, a water cooler, an ice maker, and anyapparatus having at least one of the functions thereof. Although typicalwater purifiers are exemplified for the convenience of description, suchwater purifiers should be understood merely as examples of watertreatment apparatuses according to exemplary embodiments of the presentinvention.

In the following description, the water treatment apparatuses applicableto exemplary embodiments of the present invention relate to a reservoirtype water treatment apparatus (water purifier) that may purify watersupplied from a raw water supply unit by passing the supplied waterthrough various filters, store the filtered purified water (hereinafter,simply referred to as “purified water”) in a separate storage space, anddrain the stored purified water to the outside.

Such water treatment apparatuses remove impurity particles, heavymetals, or other harmful chemicals from raw water, such as tap water ornatural water, by filtering the raw water through filters of afiltration unit.

In addition, the water treatment apparatuses applicable to exemplaryembodiments of the present invention may be configured to sterilize andclean tanks and sterilized water flow passages by generating orreceiving sterilized water, supplying the sterilized water to the tanks,and draining the sterilized water.

In particular, the water treatment apparatuses applicable to exemplaryembodiments of the present invention may be configured to sterilize andclean tanks and sterilized water flow passages by generating sterilizedwater containing a sterilizing material, such as mixed oxidant (MO), byperforming electrolysis on only purified water, filtered while passingthrough at least some filters of a filtration unit, without addingseparate “sterilizing chemicals” or “chlorides”, and by supplying thesterilized water to the tanks and the flow passages. The term“electrolysis” as used herein includes an “oxidation-reductionreaction”. In particular, the water treatment apparatuses applicable toexemplary embodiments of the present invention may be configured togenerate sterilized water containing high-concentration MO byelectrolyzing only purified water, without adding separate chloridesthrough a chloride supply device.

According to another exemplary embodiment, the water treatmentapparatuses may be configured to sterilize and clean tanks andsterilized water flow passages by generating sterilized water by mixingchemicals and purified water, supplying the sterilized water to thetanks, and draining the sterilized water.

According to another exemplary embodiment, the water treatmentapparatuses may be configured to sterilize and clean tanks andsterilized water flow passages by storing sterilized water generated orprepared in the outside, or receiving sterilized water when needed, andsupplying the stored or received sterilized water to the tanks and theflow passages.

FIG. 2 is a schematic diagram illustrating a configuration of a watertreatment apparatus having a plurality of tanks, to which a sterilizingmethod according to an exemplary embodiment of the present invention isapplied;

A first tank 100 stores purified water having passed through afiltration unit and selectively drains the purified water. The firsttank 100 may store sterilized water supplied from a sterilizing module.

An intermediate device 300 processes the purified water supplied fromthe first tank 100. As illustrated in FIG. 2, the intermediate device300 may provide a flow passage that bypasses fluid, such as the purifiedwater or sterilized water supplied from the first tank 100, to a secondtank 200. Specifically, the intermediate device 300 may be a third tankconfigured to store the purified water supplied from the first tank 100and heat or cool the stored purified water, an ice maker configured tomake ice by cooling the supplied purified water, or a carbonated watermaker configured to make carbonated water by supplying carbon dioxide tothe purified water. In addition, the intermediate device 300 may be asyrup addition device configured to add syrup or scent to the purifiedwater. However, according to another exemplary embodiment of the presentinvention, the intermediate device 300 may not be included in the watertreatment apparatus, depending on the purpose of the water treatmentapparatus. In this case, the first tank 100 may include a separate flowpassage that bypasses fluid, such as the supplied purified water orsterilized water, to the second tank 200, and may also include a flowpassage that directly drains water from the first tank 100 to a drainpipe conduit.

Hereinafter, a water treatment apparatus including an ice maker as anexample of the intermediate devices 300 will be described.

The ice maker 300 may receive purified water from the first tank 100 andmake ice of the purified water. The ice maker 300 may employ an icemaking method using an ice tray and an immersion evaporator, and mayemploy an injection type ice making method that makes ice by injectingwater into a cooling container. Specifically, the water may be cooledusing a thermoelectric module (TEM) or evaporation heat of a refrigerantliquefied by a compressor or the like. In addition, any ice makingmethod or any cooling method may be employed as long as it can beapplied to the water treatment apparatus.

The second tank 200 may receive purified water from the first tank 100and ice from the ice maker 300 to make cold water, and store the coldwater. That is, the second tank 200 may make cold water by mixingnormal-temperature purified water and ice, and store the cold water. Inthe case in which the intermediate device 300 is not the ice maker, thesecond tank 200 may cool the stored purified water through a separatecooling device using a thermoelectric module or refrigerant gas.

The first tank 100 may be supplied with purified water or sterilizedwater through a water inlet pipe 140. Although not illustrated,sterilized water generated by an electrolytic sterilizer may be suppliedthrough the water inlet pipe 140 in a sterilizing mode.

In addition, the first tank 100 may include a first water outlet pipe110, a second water outlet pipe 130, and a water intake pipe 120.

The first water outlet pipe 110 may transfer water stored in the firsttank 100 to the ice maker 300. The first water outlet pipe 110 mayinclude a valve for controlling water flow. If necessary, water flow maybe controlled using a water jet pump.

The second water outlet pipe 130 may transfer water stored in the firsttank 100 to the second tank 200. The second water outlet pipe 130 mayinclude a valve for controlling water flow. If necessary, water flow maybe controlled using a water jet pump.

The water intake pipe 120 may drain water stored in the first tank 100to the outside. In particular, the water intake pipe 120 may beconnected to a purified water cock and transfer purified water to auser. In addition, if necessary, the water intake pipe 120 may include avalve for controlling the supply of purified water.

As illustrated in FIG. 2, the first water outlet pipe 110, the waterintake pipe 120, and the second water outlet pipe 130 may be installedon the side of the first tank 100 in order from top to bottom. Inpractice, the first water outlet pipe 110, the second water outlet pipe130, and the water intake pipe 120 are disposed on a bottom of the firsttank 100 in order for effective arrangement of purification, and aheight difference between the pipes may not be great. According toexemplary embodiments, the second water outlet pipe 130, the waterintake pipe 120, and the first water outlet pipe 110 may be installed inorder from top to bottom.

The ice maker 300 may further include a bypass passage 310 that canbypass supplied purified water to the second tank 200, without storingthe supplied purified water in an ice tray. For example, the bypasspassage 310 may serve as a passage through which ice is transferred fromthe ice tray to the second tank 200. The bypass passage 310 is used fora partial drainage of the sterilized water, as described below.

The second tank 200 may include a drain line 210, a drain valve (notillustrated), and a drain pump 220.

The drain line 210 is configured to drain water or sterilized water,stored in the second tank 200, as live water. The drain line 210 isprovided as a drain pipe conduit connected to a bottom of the secondtank 200.

The drain valve may control the opening/closing of the drain line 210,and the drain pump 220 may be installed in the drain line 210. The drainpump 220 is used to more effectively drain water stored in the secondtank 200. Even in the case that the drain valve is opened, water is notdrained rapidly if a cross-section of the drain line 210 is narrow.Since water is not drained completely, old purified water or sterilizedwater used in a sterilizing process may remain in the second tank 200.

Recent water treatment apparatuses have tended to reduce the entire sizethereof, so as to allow them to be installed in an indoor space whilesupporting various functions. Therefore, there is a significant risk inreducing a cross-sectional area of the drain line 210. Even when thedrain valve is opened, it is hard to drain water completely. Hence, thedrain pump 220 may also be provided together with the drain valve.

In general, the drain pump 220 may be provided with a motor. The motormay be a DC motor capable of controlling an operating speed using aninput voltage, or an AC motor capable of controlling an operating speedthrough a frequency regulation. In general, the drain valve may beprovided with a latch valve.

Although not illustrated, an electrolytic sterilizer may be installed inthe water inlet pipe 140. The electrolytic sterilizer may be configuredto generate sterilized water, including a sterilizing material such asmixed oxidant (MO), through electrolysis using only purified waterfiltered by at least some of filters provided in the filtration unit.

The electrolytic sterilizer sterilizes or destroys microorganisms orbacteria remaining in water by passing water between electrodes ofdifferent polarities. In general, sterilization of purified water byelectrolysis may be performed by a combination of a direct oxidationreaction that directly oxidizes microorganisms with a positiveelectrode, and an indirect oxidation reaction that oxidizesmicroorganisms with a variety of mixed oxidants (for example, residualchorine, ozone, OH radicals, and oxygen radicals) that may be generatedat a positive electrode

In addition, although not illustrated, a chemical sterilizer may beinstalled in the water inlet pipe 140. The chemical sterilizer may beconfigured to generate sterilized water, including a sterilizingmaterial, using only purified water filtered by at least a part offilters provided in the filtration unit.

Furthermore, although not illustrated, a device configured to receivesterilized water from the outside may be installed in the water inletpipe 140. The device may receive and store sterilized water prepared orgenerated on the outside, or may supply the sterilized water immediatelyto the water inlet pipe 140.

Hereinafter, a method for sterilizing the above-described watertreatment apparatus having the plurality of tanks will be described.

FIG. 3 is a flow diagram illustrating a method for a water treatmentapparatus having a plurality of tanks, according to an exemplaryembodiment of the present invention.

In a sterilization preparation process S10, purified water may bedrained until a first amount of purified water is left in the first tank100. The first amount of the purified water may be determined, dependingon a target dilution level of sterilized water being supplied at highconcentration. If necessary, the first amount of the purified water maybe determined to the extent that the sterilized water is prevented fromdiffusing into the water intake pipe 120.

In a sterilizing process S20, the first tank 100 may be sterilized bysupplying sterilized water thereto. Water of the first tank 100 may bedrained into the second tank 200 through the ice maker 300 until asecond amount of water is left therein. The second amount of waterremaining in the first tank 100 may be drained into the second tank 200.Alternatively, according to exemplary embodiments, after the secondamount of water is drained into the second tank 200, water remaining inthe first tank 100 may be drained into the second tank 200 through theice maker 300.

That is, after the first tank 100 is sterilized by supplying sterilizedwater thereto, sterilized water may be divided and drained. This isundertaken to prevent sterilized water from diffusing into the waterintake pipe 120. When the second amount of water is stored in the firsttank 100, a height of a water surface may fall to within a range betweena height of the water intake pipe 120 and a height of the first wateroutlet pipe 110.

That is, by draining upper sterilized water and lower sterilized waterdrained through different pipes, the diffusion of sterilized water intothe water intake pipe 120 may be minimized. A detailed descriptionthereof will be given below.

In a cleaning process S30, the first tank 100 may be cleaned bysupplying purified water thereto. The purified water used to clean thefirst tank 100 may be drained into the second tank 200, and the secondtank 200 may be cleaned with the purified water drained thereinto. Evenin the case that the sterilized water is drained, the sterilized watermay remain in several places in the first tank 100 and the second tank200. In this case, the remaining sterilized water may be washed out bythe purified water.

In addition, after the sterilization preparation process S10 and thesterilizing process S20, purified water and sterilized water remainingin the second tank 200 may be drained. Furthermore, when the cleaningprocess 30 is completed, purified water may be supplied to the firsttank 100, so that a user can drink the purified water. This may be doneafter or during the draining of the purified water used to clean thesecond tank 200.

As described above, the method for sterilizing the water treatmentapparatus may sterilize and clean the plurality of tanks whileminimizing the diffusion of sterilized water into the water intake pipe120.

FIG. 4 is a flow diagram illustrating a detailed flow of thesterilization preparation process in the method for sterilizing thewater treatment apparatus, according to an exemplary embodiment of thepresent invention;

Referring to FIG. 4, the sterilization preparation process S10 accordingto an exemplary embodiment of the present invention may include apurified water supplying process S11, a cold water draining process S12,and a partial purified water draining process S13, and may furtherinclude a cold water draining process S14.

In the purified water supplying process S11, a preset volume of purifiedwater may be supplied to the first tank 100. In the cold water drainingprocess S12, cold water remaining in the second tank 200 may be drained.In the purified water supplying process S11, a preset volume of purifiedwater may be supplied to the first tank 100 using a flowmeter, which maybe provided in the water inlet pipe 140, or by a method of measuring aperiod of time during which purified water is supplied to the first tank100. However, an amount of purified water remaining in the first tank100 is difficult to measure unless an amount of purified water suppliedor used is continuously tracked. Therefore, an amount of purified waterremaining in the first tank 100 may be exactly determined by fullyfilling the first tank 100 with purified water. That is, the presetvolume may be set to a maximum storage amount of the first tank 100.

In addition, when cold water remains in the second tank 200, a desiredamount of purified water may not be drained from the first tank 100.Therefore, it is necessary to drain water completely from the secondtank 200 in the cold water draining process S12.

In the partial purified water draining process S13, purified water fromthe first tank 100 may be drained into the second tank 200 during afirst draining period. The first draining period may be a period of timetaken until an amount of water corresponding to a difference between thepreset volume and the first amount of water is drained from the firsttank 100 to the second tank 200. On the other hand, as described above,when the preset volume is set to a maximum storage amount of the firsttank 100, the first draining period may be a period of time taken untilan amount of water corresponding to a difference between the maximumstorage amount of the first tank 100 and the first amount of water isdrained from the first tank 100 to the second tank 200. The firstdraining period may be determined by the maximum storage amount of thefirst tank 100, the first amount of water, an amount of drainage of thesecond water outlet pipe 130 per unit time, or the like, and may bepreviously determined in designing the water treatment apparatus.Therefore, the first draining period may be calculated theoretically orexperimentally in designing the water treatment apparatus. That is, inthe partial purified water draining process S13, purified water may bedrained during the first draining period determined using an estimatedamount of the remaining purified water (full water level through thesupply of purified water), a drainage rate, and the first amount ofwater. Alternatively, in the partial purified water draining processS13, a flowmeter may be used. Specifically, a flowmeter may be providedin the water outlet pipe of the first tank 100. When an amount of watercorresponding to a difference between the preset volume and the firstamount of water is drained into the second tank 200, the drainage ofwater may be stopped. In this case, as compared to a case in which wateris drained during the first period of time, an exact amount of purifiedwater may be drained into the second tank 200.

In the cold water draining process S14, purified water drained from thefirst tank 100 may be drained from the second tank 200, such that thesecond tank 200 is ready to store water drained from the first tank 100or the ice maker 300.

FIG. 5 is a flow diagram illustrating a detailed flow of the sterilizingprocess in the method for sterilizing the water treatment apparatus,according to an exemplary embodiment of the present invention;

Referring to FIG. 5, the sterilizing process S20 according to anexemplary embodiment of the present invention may include a sterilizedwater supplying process S21, an upper sterilized water draining processS22, and a lower sterilized water draining process S23, and may furtherinclude a cold water draining process S24.

In the sterilized water supplying process S21, the first tank 100 may besupplied with sterilized water through a water inlet pipe 140. Inaddition, the supplied sterilized water may sterilize a lower portion ofthe first tank 100 while diffusing into the remaining purified water.However, it takes a time for the sterilized water to completely diffuseinto the purified water. Therefore, if only the sterilized water isdrained before the sterilized water completely diffuses into the lowerportion of the first tank 1, the diffusion of the sterilized water intothe water intake pipe 120 may be minimized.

As described above, when assuming that the first water outlet pipe 110,the water intake pipe 120, and the second water outlet pipe 130 areinstalled on the side of the first tank 100 in order from top to bottom,sterilized water stored in an upper portion of the first tank 100 may bedrained into the ice maker 300 through the first water outlet pipe 110in the upper sterilized water draining process S22. The sterilized waterdrained into the ice maker 300 may be transferred to the second tank 200along the bypass passage 210 of the ice maker 300. That is, when thesterilized water is drained through the second water outlet pipe 130,high-concentration sterilized water may gradually move downward and flowdirectly into the water intake pipe 120. However, if sterilized water isdrained into the ice maker 300 through the first water outlet pipe 110,sterilized water stored in a portion higher than the water intake pipe120 is continuously drained. Therefore, the inflow of the sterilizedwater into the water intake pipe 120 may be minimized. In addition,since the lower portion of the first tank 100 may be sterilized with thediffused sterilized water, there is no problem in sterilizing the lowerportion of the first tank 100. In order to drain only the uppersterilized water, the sterilized water may be drained into the ice maker300 during a second draining period in the upper sterilized waterdraining process S22. The second draining period may be a period of timetaken until an amount of water corresponding to a difference between thepreset volume and a second amount of water is drained through the firstwater outlet pipe 110. As described above, in the second amount ofwater, a height of a water surface of the first tank 100 may fall towithin a range between a height of the water intake pipe 120 and aheight of the first water outlet pipe 110. The preset volume may be amaximum storage amount of the first tank 100. Therefore, the seconddraining period may be determined, considering the maximum storageamount of the first tank 100, the second amount of water, and an amountof drainage of the first water outlet pipe 110 per unit time.

A flowmeter may be directly provided in the first water outlet pipe 110to adjust an amount of sterilized water that is drained from the firsttank 100. That is, an amount of sterilized water drained from the firsttank 100 may be measured using the flowmeter, and the drainage of waterfrom the first tank 100 may be stopped when the measured amount ofsterilized water is equal to a difference between the maximum storageamount of the first tank 100 and the second amount of water. In thiscase, although a separate flowmeter is required, an exact amount ofsterilized water may be drained from the first tank 100, as compared toa case in which water is drained during the second draining period.

In the lower sterilized water draining process S23, the purified waterremaining in the first tank 100 and the diffused sterilized water may bedrained into the second tank 200 through the second water outlet pipe130. Therefore, the lower portion of the first tank 100 may besterilized, and the sterilized water may be completely drained.

In the cold water draining process S24, water stored in the second tank200 may be drained, and the second tank 200 may be ready to receivewater drained from the first tank 100.

According to exemplary embodiments, the second water outlet pipe 130,the water intake pipe 120, and the first water outlet pipe 110 may beinstalled on the side of the first tank 100 in order from top to bottom.In this case, in the sterilizing process 20, water may be directlydrained into the second tank 200 through the second water outlet pipe130. If the second amount of water is left in the first tank 100, watermay be bypassed to the ice maker 300 through the first water outlet pipe110. Therefore, in this case, the inflow of sterilized water into thewater intake pipe 120 may be minimized.

FIG. 6 is a flow diagram illustrating a detailed flow of the cleaningprocess in the method for sterilizing the water treatment apparatus,according to an exemplary embodiment of the present invention.

Referring to FIG. 6, the cleaning process S30 according to an exemplaryembodiment of the present invention may include a washing watersupplying process S31 and a washing water draining process S32, and mayfurther include a cold water draining process S33. In addition, asdescribed above, a purified water supplying process may be performed atthe same time as the cold water draining process S33, or may beperformed prior to the cold water draining process S33.

In the washing water supplying process S31, a preset volume of purifiedwater may be supplied through the water inlet pipe 140, and the firsttank 100 may be cleaned with the supplied purified water. The presetvolume may be a maximum storage amount of the first tank 100 so as toclean the entirety of the first tank 100.

In the washing water draining process S32, purified water used to cleanthe first tank 100 may be drained into the second tank 200. That is, thefirst tank 100 is emptied so that purified water may be stored therein.In addition, the purified water drained into the second tank 200 mayclean the second tank 200. If necessary, the first water outlet pipe 110may be cleaned by draining some of the washing water into the ice maker300.

Since the purified water supplying process and the cold water drainingprocess S33 have been described above, a detailed description thereofwill be omitted.

The above-described processes may prevent a problem in which sterilizedwater flows into the water intake pipe 120, and thus, a user drinkswater containing sterilized water after the sterilizing and cleaningprocess. Furthermore, a plurality of tanks may be sterilized andcleaned.

Hereinafter, an example in which the sterilizing method is applied to awater treatment apparatus having a plurality of tanks will be describedwill be described.

A mode for sterilizing and cleaning the water treatment apparatus isdriven by a user' input or in a preset period or time point.

In step 1, the first tank 100 is filled with purified water through thewater inlet pipe 140 up to a full water level.

In step 2, water of the second tank 200 is completely drained, or isdrained until 430 seconds have elapsed. 430 seconds are enough time tocompletely drain water from the second tank 200.

In step 3, water of the first tank 100 is drained into the second tank200 for 110 seconds.

In step 4, water of the second tank 200 is completely drained, or isdrained until 370 seconds have elapsed. 370 seconds are enough time tocompletely drain water from the second tank 200.

In step 5, the first tank 100 is filled with sterilized water throughthe water inlet pipe 140 up to a full water level.

In step 6, sterilized water of the first tank 100 is drained into theice maker 300 through the first water outlet pipe 110 for 180 seconds.

In step 7, sterilized water of the first tank 100 is drained into thesecond tank 200 through the second water outlet pipe 130 for 70 seconds.

In step 8, water of the second tank 200 is completely drained, or isdrained until 430 seconds have elapsed. 430 seconds are enough time tocompletely drain water of the second tank 200.

In step 9, the first tank 100 is filled with purified water through thewater inlet pipe 140 up to a full water level.

In step 10, water of the first tank 100 is drained into the second tank200 for 230 seconds.

In step 11, water of the second tank 200 is completely drained, or isdrained until 430 seconds have elapsed. 430 seconds are enough time tocompletely drain water from the second tank 200.

A display device, such as an LED, may be used to indicate to the userthat the sterilizing function is being executed. For example, an LED forsterilization indication may be turned on and off (ON for 3 seconds, OFFfor 1 second), and a front LED may be dimmed as a whole.

In addition, the drain valve and the drain pump 220 installed in thesecond tank 200 may be operated with constant time difference, so as toprevent the drain valve from malfunctioning due to a drainage pressureof the drain pump 200.

When the intermediate device is operating, for example, when the icemaker 300 makes ice, the sterilizing process may be started after theoperation of the intermediate device is completed, for example, afterthe ice making process is completed.

In addition, if purified water or sterilized water does not reach a fullwater level within a predetermined time, such a case may be recognizedas an emergency situation, such as an interruption of a water supply,and the sterilizing operation may be restarted later. The watertreatment apparatus may inform the user of the emergency situationthrough the display device.

FIG. 7 is a schematic diagram illustrating a configuration of a watertreatment apparatus having a plurality of tanks, to which a sterilizingmethod according to another exemplary embodiment of the presentinvention is applied.

A first tank 100 may store purified water having passed through afiltration unit, and selectively drain the purified water. The firsttank 100 may store sterilized water which flows in from a sterilizingmodule.

A second tank 200 may receive purified water from the first tank 100,make cold water, and store the cold water. That is, the second tank 200may make cold water by cooling normal-temperature purified water using acooler, and store the cold water.

The intermediate device 300 processes cold water supplied from thesecond tank 200. Specifically, the intermediate device 300 may be athird tank configured to store the cold water supplied from the firsttank 200 and heat or cool the stored cold water, an ice maker configuredto make ice by cooling the supplied cold water, or a carbonated watermaker configured to make carbonated water by supplying carbon dioxide tothe cold water. In addition, the intermediate device 300 may be a syrupaddition device configured to add syrup or scent to the cold water.

Hereinafter, a water treatment apparatus including an ice maker as anexample of the intermediate devices 300 will be described.

The ice maker 300 may receive cold water from the second tank 200 andmake ice. The ice maker 300 may employ various ice making methods, forexample, an ice making method using an ice tray and an immersionevaporator, or an injection type ice making method that makes ice byinjecting water into a cooling container.

The first tank 100 may be supplied with purified water or sterilizedwater through a water inlet pipe 140. Although not illustrated,sterilized water generated by an electrolytic sterilizer may be suppliedthrough the water inlet pipe 140 in a sterilizing mode.

In addition, the first tank 100 may include a second water outlet pipe130 and a water intake pipe (not illustrated).

The second outlet pipe 130 may transfer water stored in the first tank100 to the second tank 200. The second water outlet pipe 130 may includea valve for controlling water flow. If necessary, water flow may becontrolled using a water jet pump.

The water intake pipe may drain water stored in the first tank 100 tothe outside. In particular, the water intake pipe may be connected to apurified water cock and transfer purified water to a user. In addition,if necessary, the water intake pipe may include a valve for controllingthe supply of purified water.

The ice maker 300 may further include a flow passage 330 that candischarge supplied cold water, without storing the supplied cold waterin an ice tray. An intermediate device other than the ice maker 300 mayalso further include a flow passage 330 that can discharge supplied coldwater, without storing the supplied cold water.

The second tank 200 may include a drain line 210, a drain valve (notillustrated), a drain pump 220, a third water outlet pipe 240, and awater intake pipe (not illustrated).

The drain line 210 is configured to drain water or sterilized water,stored in the second tank 200, as live water. The drain line 210 isprovided as a drain pipe conduit connected to a bottom of the secondtank 200.

The drain valve may control the opening/closing of the drain line 210,and the drain pump 220 may be installed in the drain line 210. The drainpump 220 is used to more effectively drain water stored in the secondtank 200. Even in the case that the drain valve is opened, water is notdrained rapidly if a cross-section of the drain line 210 is narrow.Since water is not drained completely, old purified water or sterilizedwater used in a sterilizing process may remain in the second tank 200.

The third water outlet pipe 240 may transfer water stored in the secondtank 200 to the ice maker 300. The third water outlet pipe 240 mayinclude a valve for controlling water flow. If necessary, water flow maybe controlled using a water jet pump.

Although not illustrated, an electrolytic sterilizer may be installed inthe water inlet pipe 140. The electrolytic sterilizer may be configuredto generate sterilized water, including a sterilizing material such as amixed oxidant (MO), through electrolysis using only purified waterfiltered by at least a part of filters provided in the filtration unit.

In addition, although not illustrated, a chemical sterilizer may beinstalled in the water inlet pipe 140. The chemical sterilizer may beconfigured to generate sterilized water, including a sterilizingmaterial, using only purified water filtered by at least a part offilters provided in the filtration unit.

Furthermore, although not illustrated, a device configured to receivesterilized water from the outside may be installed in the water inletpipe 140. The device may receive and store sterilized water prepared orgenerated in the outside, or may supply the sterilized water immediatelyto the water inlet pipe 140.

FIG. 8 is a flow diagram illustrating a method for sterilizing a watertreatment apparatus having a plurality of tanks, according to anotherexemplary embodiment of the present invention.

In a sterilization preparation process S100, purified water from thefirst tank 100 may be drained through the second water outlet pipe 130until a first amount of purified water is left in the first tank 100.Purified water from the second tank 200, drained from the first tank100, may be drained through the third water outlet pipe 240 until asecond amount of purified water is left in the second tank 200. Thefirst amount and the second amount may be determined, depending on atarget dilution level of sterilized water being supplied at highconcentration.

In a first sterilizing process S210, the first tank 100 may besterilized by supplying sterilized water thereto. Water of the firsttank 100 may be drained into the second tank 200 through the secondwater outlet pipe 130 until a third amount of water is left therein.

In a second sterilizing process S220, a fourth amount of sterilizedwater drained into the second tank 200 may be drained into the ice maker300 through the third water outlet pipe 240. In particular, in thesecond sterilizing process S220, sterilized water may be drained fromthe second tank 200 during a fourth draining period, a period of timetaken to drain the fourth amount of water from the second tank 200. Anamount of drainage may be controlled by adjusting a draining period,without using a water level sensor or the like. The third water outletpipe 240 may further include a flow rate sensor. In the secondsterilizing process S220, the drainage of water from the second tank 200may be stopped when the measured amount of drainage becomes equal to thefourth amount of water.

In a third sterilizing process S230 a, sterilized water remaining in thefirst tank 100 may be drained into the second tank 200 through thesecond water outlet pipe 130.

In a fourth sterilizing process S240, sterilized water stored in thesecond tank 200 may be drained through the drain line 210.

Through the first to fourth sterilizing processes S210 to S240, thesecond water outlet pipe 130 and the third water outlet pipe 240, aswell as the first tank 100 and the second tank 200, may be sterilized.

In a cleaning process S300, the first tank 100 may be cleaned bysupplying purified water thereto. The purified water used to clean thefirst tank 100 may be drained into the second tank 200, and the secondtank 200 may be cleaned with the purified water drained thereinto.Furthermore, a part of the purified water used to clean the second tank200 may be drained into the ice maker 300, and washing water remainingin the second tank 200 may be drained through the drain line 210. Evenin the case that the sterilized water is drained, the sterilized watermay remain in several places in the first tank 100 and the second tank200. In this case, the remaining sterilized water may be washed out bythe purified water. In addition, the second water outlet pipe 130 andthe third water outlet pipe 240 also may be cleaned.

Furthermore, when the cleaning process is completed, purified water maybe supplied to the first tank 100 so as to allow a user to drink water.This may be done after or during the draining of the purified water usedto clean the second tank 200.

As described above, the method for sterilizing the water treatmentapparatus may sterilize and clean the plurality of tanks and flowpassages.

FIG. 9 is a flow diagram illustrating a detailed flow of thesterilization preparation process in the method for sterilizing thewater treatment apparatus having a plurality of tanks, according toanother exemplary embodiment of the present invention;

In a second tank draining process S110, cold water remaining in thesecond tank 200 may be drained. When cold water remains in the secondtank 200, a desired amount of purified water may not be drained from thefirst tank 100. Therefore, it is necessary to completely drain waterfrom the second tank 200.

In a first purified water supplying process S120, a preset volume ofpurified water may be supplied to the first tank 100. However, asdescribed above, an amount of purified water remaining in the first tank100 is difficult to measure unless an amount of purified water suppliedor used is continuously tracked. An amount of purified water remainingin the first tank 100 may be exactly determined by setting the presetvolume as a maximum storage amount of the first tank 100 and fullyfilling the first tank 100 with purified water.

In a first partial purified water draining process S130, purified waterfrom the first tank 100 may be drained into the second tank 200 during afirst draining period. The first draining period may be a period of timetaken until an amount of water corresponding to a difference between thepreset volume and the first amount of water is drained from the firsttank 100 to the second tank 200. When the preset volume is a maximumstorage amount of the first tank 100, the first draining period may be aperiod of time taken until an amount of water corresponding to adifference between the maximum storage amount of the first tank 100 andthe first amount of water is drained from the first tank 100 to thesecond tank 200. The first draining period may be determined by themaximum storage amount of the first tank 100, the first amount of water,an amount of water drained per unit time from the second water outletpipe 130, or the like, and may be previously determined in designing thewater treatment apparatus. Therefore, the first draining period may becalculated theoretically or experimentally in designing the watertreatment apparatus. That is, in the first partial purified waterdraining process S130, purified water may be drained during the firstdraining period of time determined using an estimated amount of theremaining purified water (full water level through the supply ofpurified water), a drainage rate, and the first amount of water.

In a second partial purified water draining process S140, the purifiedwater drained from the first tank 100 may be drained during a seconddraining period, such that the second tank 200 is ready to store waterdrained from the first tank 100. A concentration of sterilized waterused to sterilize the second tank 200 may be adjusted. The seconddraining period is a period of time taken to drain an amount of watercorresponding to a result of a subtraction of the first amount of waterand the second amount of water from the set volume.

As described above, instead of setting the first draining period and thesecond draining period, an amount of drainage may be directly measuredusing a flowmeter. That is, an amount of water drained from the firsttank 100 and an amount of water drained from the second tank 200 aredirectly measured using the flowmeter, and the drainage of water may bestopped when the preset amount of water has been drained.

FIG. 10 is a schematic diagram illustrating a configuration of a watertreatment apparatus having a plurality of tanks, to which a sterilizingmethod according to another exemplary embodiment of the presentinvention is applied.

A first tank 100 may store purified water having passed through afiltration unit, and selectively drain the purified water. The firsttank 100 may store sterilized water which flows in from a sterilizingmodule.

A second tank 200 may receive purified water from the first tank 100,make cold water, and store the cold water. That is, the second tank 200may make cold water by cooling normal-temperature purified water using acooler, and store the cold water.

An intermediate device 300 processes purified water supplied from thefirst tank 100. Specifically, the intermediate device 300 may be a thirdtank configured to store the purified water supplied from the first tank100 and heat or cool the stored purified water, an ice maker configuredto make ice by cooling the supplied purified water, or a carbonatedwater maker configured to make carbonated water by supplying carbondioxide to the purified water. In addition, the intermediate device 300may be a syrup addition device configured to add syrup or scent to thepurified water.

Hereinafter, a water treatment apparatus including an ice maker as anexample of the intermediate devices 300 will be described. However, theintermediate device 300 according to an exemplary embodiment of thepresent invention is not limited to the ice maker. Examples of theintermediate device 300 may include various types of devices, includingthe third tank, the carbonated water maker, and the syrup additiondevice.

The ice maker 300 may be supplied with purified water from the firsttank 100 or cold water from the second tank 200, and make ice of thesupplied purified water or cold water. The ice maker 300 may employvarious ice making methods, for example, an ice making method using anice tray and an immersion evaporator, or an injection type ice makingmethod that makes ice by injecting water into a cooling container.

The first tank 100 may be supplied with purified water or sterilizedwater through a water inlet pipe 140. Although not illustrated,sterilized water generated by an electrolytic sterilizer may be suppliedthrough the water inlet pipe 140 in a sterilizing mode.

In addition, the first tank 100 may include a first water outlet pipe110, a second water outlet pipe 130, and a water intake pipe (notillustrated).

The first water outlet pipe 110 may transfer water stored in the firsttank 100 to the ice maker 300. The first water outlet pipe 110 mayinclude a valve for controlling water flow. If necessary, the firstwater outlet pipe 110 may control water flow using a water jet pump.

The second outlet pipe 130 may transfer water stored in the first tank100 to the second tank 200. The second water outlet pipe 130 may includea valve for controlling water flow. If necessary, water flow may becontrolled using a water jet pump.

The water intake pipe may drain water stored in the first tank 100 tothe outside. In particular, the water intake pipe may be connected to apurified water cock and transfer purified water to a user. In addition,if necessary, the water intake pipe may include a valve for controllingthe supply of purified water.

As illustrated in FIG. 2, the first water outlet pipe 110, the waterintake pipe, and the second water outlet pipe 130 may be installed onthe side of the first tank 100 in order from top to bottom. Therefore,sterilized water flowing into the first tank 100 may be drained into theice maker 300 through the first water outlet pipe 110, and then, thesterilized water may be drained into the second tank 200 through thesecond water outlet pipe 130. Therefore, as described above, the inflowof sterilized water into the water intake pipe may be minimized.

The ice maker 300 may further include a flow passage 330 which candischarge the supplied purified water or cold water, without storing thesupplied purified water or cold water in an ice tray. An intermediatedevice other than the ice maker 300 may also further include a flowpassage 330 that can discharge the supplied cold water, without storingthe supplied cold water.

The second tank 200 may include a drain line 210, a drain valve (notillustrated), a drain pump 220, a third water outlet pipe 240, and awater intake pipe (not illustrated).

The drain line 210 is configured to drain water or sterilized water,stored in the second tank 200, as live water. The drain line 210 isprovided as a drain pipe conduit connected to a bottom of the secondtank 200.

The drain valve may control the opening/closing of the drain line 210,and the drain pump 220 may be installed in the drain line 210. The drainpump 220 is used to more effectively drain water stored in the secondtank 200. Even in the case that the drain valve is opened, water is notdrained rapidly if a cross-section of the drain line 210 is narrow.Since water is not drained completely, old purified water or sterilizedwater used in a sterilizing process may remain in the second tank 200.

The third water outlet pipe 240 may transfer water stored in the secondtank 200 to the ice maker 300. The third water outlet pipe 240 mayinclude a valve for controlling water flow. If necessary, water flow maybe controlled using a water jet pump.

FIG. 11 is a flow diagram illustrating a method for sterilizing a watertreatment apparatus having a plurality of tanks, according to anotherexemplary embodiment of the present invention.

In a sterilization preparation process S100, purified water from thefirst tank 100 may be drained through the second water outlet pipe 130until a first amount of purified water is left in the first tank 100.Purified water from the second tank 200, drained from the first tank100, may be drained through the third water outlet pipe 240 until asecond amount of purified water is left in the second tank 200. Thefirst amount and the second amount may be determined, depending on atarget dilution level of sterilized water being supplied at highconcentration.

In a first sterilizing process S210, the first tank 100 may besterilized by supplying sterilized water thereto. Water of the firsttank 100 may be drained into the second tank 200 through the secondwater outlet pipe 130 until a third amount of water is left therein.That is, after the first tank 100 is sterilized by supplying sterilizedwater thereto, sterilized water may be divided and drained.

In a second sterilizing process S220, a fourth amount of sterilizedwater drained into the second tank 200 may be drained into the ice maker300 through the third water outlet pipe 240. In particular, in thesecond sterilizing process S220, sterilized water may be drained fromthe second tank 200 during a fourth draining period. The fourth drainingperiod is a period of time taken to drain the fourth amount of waterfrom the second tank 200. An amount of drainage may be controlled byadjusting a draining period of time, without using a water level sensoror the like. The third water outlet pipe 240 may further include a flowrate sensor. In the second sterilizing process S220, the drainage ofwater from the second tank 200 may be stopped when the measured amountof drainage becomes equal to the fourth amount of water.

In a third sterilizing process S230 b, sterilized water remaining in thefirst tank 100 may be drained into the ice maker 300 through the firstwater outlet pipe 110.

In a fourth sterilizing process S240, sterilized water stored in thesecond tank 200 may be drained through the drain line 210.

Through the first to fourth sterilizing processes S210 to S240, thefirst water outlet pipe 110, the second water outlet pipe 130, and thethird water outlet pipe 240, as well as the first tank 100 and thesecond tank 200, may be sterilized.

The first to fourth sterilizing processes S210 to S240 may not besequentially performed. That is, the third sterilizing process S230 bmay be performed after the first sterilizing process S210.Alternatively, the first sterilizing process S210 and the secondsterilizing process S220 may be performed after the third sterilizingprocess S230 b.

Specifically, in the first sterilizing process S210, sterilized water ofthe first tank 100 is drained into the second tank 200 until a thirdamount of sterilized water is left therein. Then, in the thirdsterilizing process S230 b, the second amount of water remaining in thefirst tank 100 may be drained into the ice maker 300. Then, a fourthamount of sterilized water drained into the second tank 200 in thesecond sterilizing process S220 may be drained into the ice maker 300.

In addition, the first tank 100 may be sterilized by supplyingsterilized water supplied from the sterilizing module to the first tank100. Then, as opposed to the first sterilizing process S210, thesterilized water may be drained not into the second tank 200 but intothe ice maker 300. Sterilized water of the first tank 100 may be drainedinto the ice maker 300 until a third amount of water is left in thefirst tank 100. Then, a second amount of sterilized water remaining inthe first tank 100 may be drained into the second tank 200. Finally, afourth amount of sterilized water drained from the second tank 200 maybe drained into the ice maker 300. In this manner, the sterilizingprocess may be finished.

That is, the first to fourth sterilizing processes S210 to S240 may beperformed in various orders as long as the processes can sterilize thefirst tank 100, the second tank 200, and the ice maker 300.

In a first cleaning process S310, the first tank 100 may be cleaned bysupplying purified water thereto. Some of the purified water used toclean the first tank 100 may be drained into the ice maker 300, and therest of the purified water may be drained into the second tank 200.

In a second cleaning process S320, some of the purified water used toclean the second tank 200 may be drained into the ice maker 300, andwashing water remaining in the second tank 200 may be drained throughthe drain line 210.

Even in the case that the sterilized water is drained, the sterilizedwater may remain in several places in the first tank 100 and the secondtank 200. In this case, the remaining sterilized water may be washed outby the purified water. In addition, the first water outlet pipe 110, thesecond water outlet pipe 130, and the third water outlet pipe 240 may becleaned.

Furthermore, when the cleaning process is completed, a preset volume ofpurified water may be supplied to the first tank 100 so as to allow auser to drink water. This may be done after or during the draining ofthe purified water used to clean the second tank 200.

As described above, the method for sterilizing the water treatmentapparatus may sterilize and clean the plurality of tanks and flowpassages.

A detailed flow of the sterilization preparation process S100 will bedescribed below with reference to FIG. 9. Since it is enough to adjustthe first amount and the second amount between the first tank 100 andthe second tank 200, the sterilization preparation process S100illustrated in FIG. 9 may be applied.

In the second tank draining process S110, cold water remaining in thesecond tank 200 may be drained. When cold water remains in the secondtank 200, a desired amount of purified water may not be drained from thefirst tank 100. Therefore, it is necessary to completely drain waterfrom the second tank 200.

In the first purified water supplying process S120, a preset volume ofpurified water may be supplied to the first tank 100. However, asdescribed above, an amount of purified water remaining in the first tank100 is difficult to measure unless an amount of purified water suppliedor used is continuously tracked. An amount of purified water remainingin the first tank 100 may be exactly determined by setting the presetvolume as a maximum storage amount of the first tank 100 and fullyfilling the first tank 100 with purified water.

In addition, in the first partial purified water draining process S130,purified water from the first tank 100 may be drained into the secondtank 200 during a first draining period. The first draining period maybe a period of time taken until an amount of water corresponding to adifference between the preset volume and the first amount of water isdrained from the first tank 100 to the second tank 200.

In the second partial purified water draining process S140, the purifiedwater drained from the first tank 100 may be drained during a seconddraining period, such that the second tank 200 is ready to store waterdrained from the first tank 100. A concentration of sterilized waterused to sterilize the second tank 200 may be adjusted. The seconddraining period is a period of time taken to drain an amount of watercorresponding to a result of a subtraction of the first amount of waterand the second amount of water from the set volume of the first tank100.

As described above, instead of setting the first draining period and thesecond draining period, an amount of drainage may be directly measuredusing a flowmeter. That is, an amount of water drained from the firsttank 100 and an amount of water drained from the second tank 200 aredirectly measured using the flowmeter, and the drainage of water may bestopped when the preset amount of water has been drained.

In the first to fourth sterilizing processes S210 to S240, sterilizedwater may be drained through the respective flow passages, such that thefirst water outlet pipe 110, the second water outlet pipe 130, and thethird water outlet pipe 240, as well as the first tank 100 and thesecond tank 200, are sterilized.

In addition, in the first cleaning process S310 and the second cleaningprocess S320, washing water may be drained through the respective flowpassages, such that the first water outlet pipe 110, the second wateroutlet pipe 130, and the third water outlet pipe 240, as well as thefirst tank 100 and the second tank 200, are cleaned.

FIG. 12 is a schematic diagram illustrating a configuration of a watertreatment apparatus having a plurality of tanks, to which a sterilizingmethod according to another exemplary embodiment of the presentinvention is applied.

A first tank 100 stores purified water having passed through afiltration unit and selectively drains the purified water. The firsttank 100 may store sterilized water which flows in from a sterilizingmodule.

A second tank 200 may receive purified water from the first tank 100,make cold water, and store the cold water. That is, the second tank 200may make cold water by cooling normal-temperature purified water using acooler, and store the cold water.

The intermediate device 300 processes purified water supplied from thesecond tank 100. Specifically, the intermediate device 300 may be athird tank configured to store the purified water supplied from thefirst tank 100 and heat or cool the stored purified water, an ice makerconfigured to make ice by cooling the supplied purified water, or acarbonated water maker configured to make carbonated water by supplyingcarbon dioxide to the purified water. In addition, the intermediatedevice 300 may be a syrup addition device configured to add syrup orscent to the purified water.

Hereinafter, a water treatment apparatus including an ice maker as anexample of the intermediate devices 300 will be described. However, theintermediate device 300 according to an exemplary embodiment of thepresent invention is not limited to the ice maker. Examples of theintermediate device 300 may include various types of devices, includingthe third tank, the carbonated water maker, and the syrup additiondevice.

The ice maker 300 may make ice of purified water supplied from the firsttank 100. The ice maker 300 may employ various ice making methods, forexample, an ice making method using an ice tray and an immersionevaporator, or an injection type ice making method that makes ice byinjecting water into a cooling container.

The first tank 100 may be supplied with purified water or sterilizedwater through a water inlet pipe 140. Although not illustrated,sterilized water generated by an electrolytic sterilizer may be suppliedthrough the water inlet pipe 140 in a sterilizing mode.

In addition, the first tank 100 may include a first water outlet pipe110, a second water outlet pipe 130, and a water intake pipe (notillustrated).

The first water outlet pipe 110 may transfer water stored in the firsttank 100 to the ice maker 300. The first water outlet pipe 110 mayinclude a valve for controlling water flow. If necessary, water flow maybe controlled using a water jet pump.

The second outlet pipe 130 may transfer water stored in the first tank100 to the second tank 200. The second water outlet pipe 130 may includea valve for controlling water flow. If necessary, water flow may becontrolled using a water jet pump.

The water intake pipe may drain water stored in the first tank 100 tothe outside. In particular, the water intake pipe may be connected to apurified water cock and transfer purified water to a user. In addition,if necessary, the water intake pipe may include a valve for controllingthe supply of purified water.

As illustrated in FIG. 2, the first water outlet pipe 110, the waterintake pipe, and the second water outlet pipe 130 may be installed onthe side of the first tank 100 in order from top to bottom. Therefore,sterilized water flowing into the first tank 100 may be drained into theice maker 300 through the first water outlet pipe 110, and then, thesterilized water may be drained into the second tank 200 through thesecond water outlet pipe 130. That is, as described above, the inflow ofsterilized water into the water intake pipe may be minimized.

The ice maker 300 may further include a flow passage 330 which candischarge the supplied purified water or cold water, without storing thesupplied purified water or cold water in an ice tray. An intermediatedevice other than the ice maker 300 may further include a flow passage330 which can discharge the supplied cold water, without storing thesupplied cold water. A drain pump 340 may be further included so as toincrease a drainage rate.

The second tank 200 may include a drain line 210, a drain valve (notillustrated), a drain pump 220, and a water intake pipe (notillustrated).

The drain line 210 is configured to drain water or sterilized water,stored in the second tank 200, as live water. The drain line 210 isprovided as a drain pipe conduit connected to a bottom of the secondtank 200.

The drain valve may control the opening/closing of the drain line 210,and the drain pump 220 may be installed in the drain line 210. The drainpump 220 is used to more effectively drain water stored in the secondtank 200. Even in the case that the drain valve is opened, water is notdrained rapidly if a cross-section of the drain line 210 is narrow.Since water is not drained completely, old purified water or sterilizedwater used in a sterilizing process may remain in the second tank 200.

A method for sterilizing a water treatment apparatus having a pluralityof tanks, according to another exemplary embodiment of the presentinvention, will be described with reference to FIG. 3.

In a sterilization preparation process S10, purified water from thefirst tank 100 may be drained through the second water outlet pipe 130until a first amount of purified water is left in the first tank 100.The first amount may be determined, depending on a target dilution levelof high-concentration sterilized water.

Hereinafter, the sterilization preparation process S10 will be describedin detail.

First, cold water remaining in the second tank 200 may be drained. Whencold water remains in the second tank 200, a desired amount of purifiedwater may not be drained from the first tank 100. Therefore, it isnecessary to completely drain water from the second tank 200.

Then, a preset volume of purified water may be supplied to the firsttank 100. However, an amount of purified water remaining in the firsttank 100 is difficult to measure unless an amount of purified watersupplied or used is continuously tracked. Therefore, an amount ofpurified water remaining in the first tank 100 may be exactly determinedby setting the preset volume as a maximum storage amount of the firsttank 100 and fully filling the first tank 100 with purified water.

Purified water from the first tank 100 may be drained into the secondtank 200 during a first draining period. The first draining period maybe a period of time taken until an amount of water corresponding to adifference between the preset volume and the first amount of water isdrained from the first tank 100 to the second tank 200. An amount ofwater drained from the first tank 100 to the second tank 200 may beadjusted using a flowmeter. That is, an amount of water corresponding toa difference between the preset volume and the first amount of water maybe drained using the flowmeter.

In a sterilizing process S20, the first tank 100 may be sterilized bysupplying sterilized water thereto. Water from the first tank 100 may bedrained into the second tank 200 through the second water outlet pipe130 until a second amount of water is left therein. The remaining watermay be drained into the ice maker 300 through the first water outletpipe 110. That is, after the first tank 100 is sterilized by supplyingsterilized water thereto, the sterilized water may be divided anddrained into the second tank 200 and the ice maker 300.

Specifically, the first tank 100 may be sterilized by supplyingsterilized water thereto, and the sterilized water may be drained intothe second tank 200 during a second draining period. The second drainingperiod may be a period of time taken to drain an amount of watercorresponding to a difference between the preset volume and the secondamount of water. In the sterilizing process S20, the second amount ofwater may be controlled by adjusting a draining period, without using awater level sensor or the like. After draining the sterilized water intothe second tank 200, the remaining sterilized water may be drained intothe ice maker 300.

Instead of setting the second draining period, an amount of waterdrained may be directly measured using a flowmeter. That is, an amountof water drained from the first tank 100 is directly measured using theflowmeter, and the drainage of water is stopped when an amount of watercorresponding to a difference between the preset volume and the secondamount of water has been drained.

Through the sterilizing process S20, the first water outlet pipe 110 andthe second water outlet pipe 130, as well as the first tank 100 and thesecond tank 200, may be sterilized.

In a cleaning process 30, the first tank 100 may be cleaned by supplyingpurified water thereto. Some of the purified water used to clean thefirst tank 100 may be drained into the second tank 200, and the rest ofthe purified water may be drained into the ice maker 300. Washing waterremaining in the second tank 200 may be drained through the drain line210.

Even in the case that the sterilized water is drained, the sterilizedwater may remain in several places in the first tank 100 and the secondtank 200. In this case, the remaining sterilized water may be washed outby the purified water. In addition, the first water outlet pipe 110 andthe second water outlet pipe 130 may be cleaned.

Furthermore, when the cleaning process is completed, a preset volume ofpurified water may be supplied to the first tank 100 so as to allow auser to drink water. This may be done after or during the draining ofthe purified water used to clean the second tank 200.

As described above, the method for sterilizing the water treatmentapparatus may sterilize and clean the plurality of tanks and flowpassages.

While the present invention has been shown and described in connectionwith the exemplary embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

The invention claimed is:
 1. A method for sterilizing a water treatmentapparatus including a sterilizing module, which generates or receivessterilized water and supplies the sterilized water, a first tank, and asecond tank, the method comprising: performing a sterilizationpreparation process to drain purified water from the first tank until afirst amount of purified water is left in the first tank; performing asterilizing process to sterilize the first tank by supplying thesterilized water supplied from the sterilizing module to the first tank,to drain water from the first tank through a first water outlet pipeuntil a second amount of water is left in the first tank, and to drainthe second amount of water remaining in the first tank into the secondtank through a second water outlet pipe; and performing a cleaningprocess to clean the first tank by supplying purified water to the firsttank, and to drain the purified water used to clean the first tank intothe second tank.
 2. The method of claim 1, wherein in the sterilizingprocess, water of the first tank is drained into the second tank throughthe second water outlet pipe until a second amount of water is left inthe first tank, and the second amount of water remaining in the firsttank is drained through the first water outlet pipe.
 3. The method ofclaim 1, wherein the first water outlet pipe is configured to supplywater to an intermediate device included in the water treatmentapparatus, and the intermediate device is connected to the second tankand configured to bypass water supplied from the first water outlet pipeto the second tank.
 4. The method of claim 3, wherein the intermediatedevice is any one of a third tank, an ice maker, a carbonated watermaker, and a syrup addition device.
 5. The method of claim 1, whereinthe sterilization preparation process comprises: supplying a presetvolume of purified water to the first tank; and draining the purifiedwater stored in the first tank during a first draining period, the firstdraining period being a period of time taken to drain an amount of watercorresponding to a difference between the preset volume and the firstamount of water.
 6. The method of claim 1, wherein the sterilizingprocess comprises: sterilizing the first tank by supplying a presetvolume of the sterilized water supplied from the sterilizing module tothe first tank; draining the sterilized water stored in the first tankthrough the first water outlet pipe during a second draining period; anddraining the water remaining in the first tank through the second wateroutlet pipe, the second draining period being a period of time taken todrain an amount of water corresponding to a difference between thepreset volume and the second amount of water.
 7. The method of claim 2,wherein the sterilizing process comprises: sterilizing the first tank bysupplying a preset volume of the sterilized water supplied from thesterilizing module to the first tank; draining the sterilized waterstored in the first tank through the second water outlet pipe during adraining period; and draining the water remaining in the first tankthrough the first water outlet pipe, the draining period being a periodof time taken to drain an amount of water corresponding to a differencebetween the preset volume and the second amount of water.
 8. The methodof claim 6, further comprising draining sterilized water stored in thesecond tank after the sterilizing process.
 9. The method of claim 1,wherein the cleaning process comprises: cleaning the first tank bysupplying a preset volume of purified water to the first tank; drainingthe supplied purified water stored in the first tank into the secondtank; and draining the purified water drained into the second tank. 10.The method of claim 9, wherein the purified water is supplied to thefirst tank at the same time as the draining of the purified waterdrained into the second tank, or the purified water is supplied to thefirst tank after the draining of the purified water drained into thesecond tank.
 11. The method of claim 1, wherein the water treatmentapparatus includes the first water outlet pipe, the second water outletpipe, and a water intake pipe, which are installed on a side of thefirst tank, the water intake pipe is configured to supply water storedin the first tank to a user, the first water outlet pipe is disposedabove the water intake pipe, and the second water outlet pipe isdisposed under the water intake pipe.
 12. The method of claim 11,wherein the water treatment apparatus further includes: a drain lineconfigured to drain water stored in the second tank; a drain valveconfigured to open/close the drain line; and a drain pump installed inthe drain line.
 13. The method of claim 11, wherein when the secondamount of water is stored in the first tank, a height of a water surfacefalls to within a range between a height of the water intake pipe and aheight of the first water outlet pipe.
 14. The method of claim 1,wherein the first amount of water is determined, depending on a targetdilution level of the sterilized water.
 15. The method of claim 1,wherein the sterilizing module generates the sterilized water by usingone of an electrolytic sterilizer employing electrolysis and a chemicalsterilizer employing sterilizing chemicals.